Current APU designs for both commercial and military aeronautical applications have individually mounted external accessory components, such as line replaceable units (LRUs), tubes and electrical harnesses, as well as associated mounting brackets, clamps, isolators and bolts. The assembly of so many components onto the surfaces of the APU is a complex and time-consuming process. The number of assembly steps increases the likelihood of quality problems. Furthermore, the procurement and stocking of such a multitude of individual parts increases stored inventory and therefore increases the cost of the manufactured APU.